Please try again by replacing lib/navigationlib.php file with fresh moodle lib/navigationlib.php . Also, Please remove or disable the local plugins if any plugin in local folder.
Also, Please do all the tests with Moodle default themes.
It's strange that dashboard option is not showing in dropdown.
thanks for replying. I got the issue.
I changed define('HOMEPAGE_MY', 2); to define('HOMEPAGE_MY', 1);in lib->moodlelib.php.(As I noticed in core file). Now dashboard option is visible.
But again one problem raised. It is not redirecting to dashboard page although i set in navigation. It is redirecting to index page. If you have any solution please let me know.
Thanks a ton.